Floor covering with viscoelastic dampening properties

ABSTRACT

The present invention concerns a floor covering, such as a carpet, containing a first textile planar element and a first layer which is at least partially connected to the first textile planar element over their surfaces, wherein the first layer contains viscoelastic polymer foam. The floor covering according to the invention is characterized in that the first textile planar element has a modulus of elasticity of ≧0.5 N/mm 2  to ≦2.5 N/mm 2 , that in the first layer  1  the viscoelastic polymer foam has a compression load deflection at 40% compression of ≧1 kPa to ≦10 kPa and that in the first layer the viscoelastic polymer foam has a hysteresis when determining the compression load deflection at 40% compression of ≧20% to ≦70%. The present invention also relates to a method of manufacturing a floor covering.

RELATED APPLICATIONS

This application claims benefit to German applications No. DE 10 2007 049 506.6, filed on Oct. 15, 2007 and DE 10 2008 046 667.0, filed on Sep. 10, 2008 which are incorporated by reference in their entirety for all useful purposes.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention concerns a floor covering, comprising a first textile planar element and a first layer which is at least partially connected to the first textile planar element over their surfaces, wherein the first layer comprises viscoelastic polymer foam. Such floor coverings may be, for example, carpets. The present invention further concerns a method for manufacturing such a floor covering.

2. Description of the Prior Art

Carpets may be employed in a variety of uses. In private or commercial housing spaces they can be used for heat and acoustical insulation besides being used for decorative purposes. One possibility to manufacture carpets is to anchor fibers in a carpet backing and then to subsequently back-foam the carpet backing on its rear side.

It is generally known to back-foam carpet backings with a viscoelastic foam. In this respect, DE 33 13 624 A1 discloses a flexible polyurethane foam for acoustical insulation purposes, a method for its manufacture and the use thereof. The described flexible polyurethane foam for acoustical insulation purposes with a density of less than 90 kg/m³ and a modulus of elasticity of less than 106 N/m² has a loss factor of at least 0.3 and viscoelastic properties in a temperature range of −20° C. to +80° C.

The flexible foam can be obtained by reacting an isocyanate with a polyol, wherein the polyol has at least one component with an OH number of 180 to 400. The foam is especially suitable for the absorption and dampening of airborne sound and for the dampening of solid-borne sound. According to this disclosure, the flexible polyurethane foam can be used for back-foaming the cowl or floor carpet of automobiles. In an embodiment, a specially prepared carpet, optionally with acoustical insulation sheets, was added to the foaming mould in order to reach a sufficient foam density. After application of the usual separating agent the reaction mixture was added with the mould covering closed. 2.5 to 3 minutes thereafter the formed article could be removed.

DE 39 42 330 A1 discloses a method for manufacturing flexible polyurethane soft foams with viscoelastic and solid-borne sound dampening properties in a temperature range of −20° C. to +80° C. by reacting a) a polyoxyalkylene polyol mixture comprising ai) special block polyoxypropylene-polyoxyethylene polyol mixtures with a hydroxyl number from 14 to 65 and a content of terminally bound ethylene oxide units from 2 to 9 weight-%, which can themselves be obtained by using a starter mixture with an average functionality of 2.2 to 2.8, consisting of water and glycerine or trimethylol propane or of water and glycerine and trimethylol propane and aii) at least one di- or trifunctional polyoxypropylene polyoxyethylene polyol with a content of oxyethylene units from 60 to 85 weight-% relative to the total weight of polymerizable alkylene oxide units, and a hydroxyl number from 20 to 80; b) optionally low molecular weight chain extenders with c) organic and/or modified organic polyisocyanates in the presence of d) catalysts, e) blowing agents, f) adjuvants and/or additives as well as the polyoxyalkylene polyol mixtures (a).

The flexible polyurethane foams obtained by this method can be used in the household sector, for example in back-foaming of carpets for the dampening of foot fall sound, as interior linings and in the automotive industry for the dampening of solid-borne sound, for example for the encapsulation of the motor compartment or for preventing interior noise by using layers back-foamed with these foams.

Carpet backings for the carpets used in the automotive sector for noise dampening are generally of a stiff structure because a stepping through or sinking into the carpet is found to be undesirable.

When actually using carpets with tangible and therefore comfort improving dampening properties which comprise a carpet backing that has been back-foamed with a viscoelastic foam there are several issues to be taken into consideration. If these carpets are to be used as floor coverings where persons walk over them and not only rest their feet as in automobiles, the carpet must be suitable for bearing the pressure and the shear stress. In particular, the composite of carpet backing, carpet fibers and back foam should not disintegrate.

Finally, it can be observed that walking over a pure layer of viscoelastic foam which is thick enough to achieve a sufficient dampening effect is not very comfortable. This can be attributed to the insecurity that arises when the foot sinks into the foam after hitting the foam.

From the preceding it is apparent that the need still exists for a viscoelastically dampened carpet which displays a high comfort when one is walking over it, but at the same time stands up to the stress of use.

SUMMARY OF THE INVENTION

The present invention has the object of overcoming at least one of the mentioned drawbacks in the art. In particular, the invention has the object of providing such a carpet.

According to the invention this object is achieved by a floor covering, comprising a first textile planar element and a first layer which is at least partially connected to the first textile planar element over their surfaces, wherein the first layer comprises viscoelastic polymer foam.

The floor covering according to the invention is characterized in that the first textile planar element has a modulus of elasticity of ≧0.5 N/mm² to ≦2.5 N/mm², that in the first layer the viscoelastic polymer foam has a compression load deflection at 40% compression of ≧1 kPa to ≦10 kPa and that in the first layer the viscoelastic polymer foam has a hysteresis when determining the compression load deflection at 40% compression of ≧20% to ≦70%.

A BRIEF DESCRIPTION OF THE INVENTION

FIG. 1 shows a floor covering according to the invention.

FIG. 2 shows another floor covering according to the invention.

FIG. 3 shows another floor covering according to the invention.

FIG. 4 shows another floor covering according to the invention.

A DETAILED DESCRIPTION OF THE INVENTION

As used herein, the singular terms “a” and “the” are synonymous and used interchangeably with “one or more.” Accordingly, for example, reference to “a fiber” herein or in the appended claims can refer to a single fiber or more than one fiber. Additionally, all numerical values, unless otherwise specifically noted, are understood to be modified by the word “about.”

In the sense of the present invention a floor covering not only means carpets, foot mats and the like, but is also to be understood as seating cushions for furniture or as mattresses.

The first textile planar element may, for example, be a woven fabric, a fibrous non-woven layer, a fleece or be knitted. Additionally, fibers may protrude from the first textile planar element, so that an assembly corresponding to a carpet backing is achieved. Furthermore, the textile may also be embedded in a polymer. The first textile planar element is connected to the first layer over their surfaces, meaning that the main surfaces of both are facing each other. In other words, the first textile planar element and the first layer are stacked on top of each other.

According to the invention the first textile planar element has a modulus of elasticity of ≧0.5 N/mm² to ≦2.5 N/mm². This is to be understood as the modulus of elasticity for stretching along the direction of the plane of the planar element. The modulus of elasticity can also be in a range from ≧0.8 N/mm² to ≦2.0 N/mm² or in a range from ≧1.0 N/mm² to ≦1.5 N/mm². The modulus of elasticity is determined using the norm DIN 53504/ISO 37. It may be provided that the first textile planar element, for example in the case of a knitted fabric, displays an elasticity of stretching the fabric and, after further elongation, an elasticity of the individual threads of the textile. In this case the selected modulus of elasticity according to the invention means the elasticity of stretching the fabric.

The connection has the effect that mechanical forces, especially shear stress, are transferred from the first textile planar element to the first layer. The connection can be a substance-to-substance connection, a force-fitting connection or a form-fitting connection. Examples for suitable connections are adhesives, welding, back-foaming of the first textile planar layer with materials leading to the polymer foam, hook and loop fasteners, zippers, push buttons and/or sewing.

The connection may be realized completely or also partially. A partial connection can be achieved by selectively creating connection spots or by arranging them in a certain pattern.

The first layer comprises viscoelastic polymer foam. Primarily, this means that besides the viscoelastic polymer foam additional components such as fillers, colorants, etc. may be present. The polymer foam may have a uniform density or the density may vary according to the location within the foam such as in integral foams. Examples for suitable polymer classes are polyurethane, polyethylene, polypropylene, polystyrene, acrylonitrile-butadiene-styrene (ABS) and polycarbonate or natural or synthetic latex. The first layer may have, for example, a thickness of ≧10 mm to ≦60 mm, preferably of ≧15 mm to ≦30 mm.

The viscoelastic properties of the polymer foam in the first layer lead to a time-delayed entry of energy into the foam. They are firstly characterized in that the compression load deflection at 40% compression is from ≧1 kPa to ≦10 kPa. This compression load deflection can also be in the range of ≧1.1 kPa to ≦3 kPa or from ≧1.2 kPa to ≦2 kPa. Furthermore, the viscoelasticity of the polymer foam is characterized by a hysteresis when determining the compression load deflection at 40% compression of ≧20% to ≦70%. The hysteresis can also be in a range of ≧30% to ≦60% or from ≧35% to ≦50%

The compression load deflection or CLD is measured according to DIN EN ISO 3386-1-98 at 23° C.±2° C., 50%±5% relative humidity, 40% compression, 1. measurement cycle. The CLD is given in kPa (kilopascal). The hysteresis in percent is also measured according to DIN EN ISO 3386-1-98. It is calculated from the quotient of the area enclosed between the characteristic curves for stress and recovery, multiplied by 100. The hysteresis number gives an information about the ratio of applied and dissipated energy. Small hysteresis numbers, such as around 5%, indicate predominantly elastic behavior. Large hysteresis numbers, such as around 90%, indicate predominantly viscous (plastic) behavior.

Alternatively, the viscoelastic polymer foam may be characterized in that the foam has an impact resilience, measured according to DIN EN ISO 8307, of ≧1% to ≦15%. This impact resilience may also be in a range of ≧3% to ≦10% or from ≧5% to ≦9%.

The viscoelastic polymer foam may also have a density according to DIN EN ISO 3386-1-98 of ≧45 kg/m³ to ≦120 kg/m³, preferably of ≧50 kg/m³ to ≦70 kg/m³, a tensile strength according to DIN EN ISO 1798-1-00 of ≧50 kPa to ≦90 kPa, an elongation according to DIN EN ISO 1798-1-00 of ≧150% to ≦210%, a compression set under dry conditions according to DIN EN ISO 1856-2000 of ≧2% to ≦5% and a compression set at 75% compression and 95% humidity according to DIN EN ISO 1856-96 of ≧2% to ≦5%.

In the present invention the comfortable sensation when walking over the floor covering is effected by the selected combination of the elasticity of the first textile planar element and the viscoelasticity of the polymer foam layer. For further elucidation it should be envisioned how a person walks over the floor covering according to the invention. In a first phase the foot with its heel or the shoe heel is placed on the floor covering. This is accompanied by a high pressure on the covering. Due to the elasticity of the first textile planar element this concentrated load is absorbed. Further into the walking process the person performs a rolling motion with the foot until the entire foot stands on the floor covering. This rolling motion is dampened by the viscoelastic polymer foam of the first layer. Finally, the foot performs another rolling motion until the ball of the foot or the tip of the toe are left touching the floor covering. In the subsequent pushing away motion from the floor the mechanical forces are dampened or transmitted back, respectively. The end result is a comfortable feeling when walking, which also does not lead to tiring due to a too soft floor. The floor covering is also protected by the elastic first textile planar element so that particularly the first layer with the polymer foam is not damaged during walking over it.

In an embodiment of the present invention the viscoelastic polymer foam of the first layer is a polyurethane foam. Polyurethanes are especially suited for the polymer foam layer according to the invention because their viscoelasticity can be tuned over a wide range. The monomers of the polyurethane foam can be selected from the group comprising polyether polyols and/or polyester polyols or their mixtures and at least difunctional isocyanates from the groups of aliphatic or aromatic isocyanates and generally known adjuvants, catalysts and stabilizers. Examples for this are given in the patent documents already cited or also in EP 0 331 941 A1.

In a further embodiment of the present invention the viscoelastic polymer foam of the first layer is a cross-linked frothed foam from synthetic or natural latex.

In a further embodiment of the present invention the material of the first textile planar element comprises polyurethane and/or thermoplastic polyurethane.

In a further embodiment of the present invention the connection between the first textile planar element and the first layer is effected by an elastomeric adhesive. According to the invention especially suitable adhesives are one and two component polyurethane adhesives. Such one component adhesives comprise isocyanate containing prepolymers which cure under the influence of moisture. The corresponding two component adhesives comprise a polyol component and an isocyanate component and are mixed prior to application. Preferably the cured adhesive layer has a modulus of elasticity, determined according to DIN EN ISO 527, of ≧100 MPa to ≦1500 MPa, of ≧300 MPa to ≦1000 MPa or of ≧500 MPa to ≦800 MPa. Using an elastomeric adhesive allows for a simple manufacturing of the floor covering according to the invention from separately available parts. Additionally, the desired effect according to the invention when walking over the floor covering is also given due to the elasticity.

In a further embodiment of the present invention fibers penetrate the first textile planar element and into the first layer and the fibers are anchored in the first layer by an elastomeric adhesive. These fibers lead to an additional strengthening of the connection between the first textile planar element and the first layer. This increases the resilience to shear stresses. Suitable according to the invention are especially elastomeric one and two component polyurethane adhesives. The fibers may also protrude externally from the first textile planar element and constitute the stepping surface of the floor covering. The fibers may be incorporated into the first textile planar element by methods such as tufting.

In a further embodiment of the present invention the first layer additionally comprises an embedded second textile planar element which has a modulus of elasticity of ≧1000 N/mm² to ≦2000 N/mm². This is to be understood as the modulus of elasticity for stretching along the direction of the plane of the planar element. The modulus of elasticity is determined using the norm DIN 53504/ISO 37. It also be in a range of ≧1200 N/mm² to ≦1800 N/mm² or of ≧1400 N/mm² to ≦1600 N/mm². The second textile planar element may, for example, be a woven fabric, a fibrous non-woven layer, a fleece or be knitted. Advantageously it is oriented to the first layer with its surface, meaning that the two major surfaces of second textile planar element and first layer are facing each other.

While the second textile planar element, vertically seen, may in general be located at any height within the first layer, it is advantageous if it is located at the lower end of the first layer, towards the floor. The incorporation of a second textile planar element with elastic properties selected according to the invention has the effect that the horizontal tearing strength of the floor covering is increased. Furthermore, the introduction of a comparatively high horizontal modulus of elasticity serves to increase the horizontal dimensional stability of the floor covering. By the positioning at the lower end of the first layer the influence that the second textile planar element has on the dampening properties of the other components of the floor covering is reduced. Therefore, a vertical dampening gradient with the associated comfortable sensation can still be established while a person is walking over the floor covering. By way of example, the second textile planar element may be connected to the first layer in a form-fitting connection, in a substance-to-substance connection or it may be integrated into the foam of the first layer.

In a further embodiment of the present invention the floor covering further comprises a second layer arranged on the side of the first layer which is opposite to the first textile planar element and which is at least partially, for example via substance-to-substance, connected to the first layer, wherein the second layer comprises polymer foam which has a compression load deflection at 40% compression of ≧15 kPa to ≦150 kPa. A substance-to-substance connection may be realized by an adhesive or by welding. Suitable according to the invention are elastomeric one and two component polyurethane adhesives. The second layer may, for example, have a thickness of ≧10 mm to ≦40 mm, preferred of ≧15 mm to ≦30 mm.

A polymer foam with the above mentioned compression load deflections may be a flocculated polyurethane foam. The polymer foam may also have a density according to DIN EN ISO 3386-1-98 of ≧60 kg/m³ to ≦200 kg/m³, a tensile strength according to DIN EN ISO 1798-1-00 of ≧40 kPa to ≦150 kPa and an elongation according to DIN EN ISO 1798-1-00 of ≧40% to ≦90%. The high compression load deflections and restoring forces are employed and a stiffer layer on the floor side of the floor covering is provided. This has the advantage that the heel of the foot or of the shoe is supported better when stepping on the floor covering. The comfort is increased when walking over the floor covering while at the same time the thickness of the first layer can be kept low. An additional advantage is cost savings due to the use of the cheaper flocculated foam.

In an embodiment of the above mentioned floor covering comprising the second layer it further comprises a third textile planar element which has a modulus of elasticity of ≧1000 N/mm² to ≦2000 N/mm², wherein the third textile planar element is arranged on the side of the second layer which is opposite to the first layer and wherein the third textile planar element is at least partially connected to the second layer. The mentioned modulus is to be understood as the modulus of elasticity for stretching along the direction of the plane of the planar element.

The modulus of elasticity is also determined using the norm DIN 53504/ISO 37. It also be in a range of ≧1200 N/mm² to ≦1800 N/mm² or of ≧1400 N/mm² to ≦1600 N/mm². The third textile planar element may, for example, be a woven fabric, a fibrous non-woven layer, a fleece or be knitted.

It is advantageous if the second layer is located on the side of the first layer which is opposite to the first textile planar element and if the second layer is at least partially connected to the first layer by a substance-to-substance connection. In this respect, it is also advantageous if the third textile planar element is located on the side of the second layer which is opposite to the first layer and if it is at least partially connected to the second layer.

Generally speaking, the arrangement of this embodiment has the advantage that that the horizontal tearing strength of the floor covering is increased. Furthermore, the introduction of a comparatively high horizontal modulus of elasticity serves to increase the horizontal dimensional stability of the floor covering. By the positioning at the lower end of the second layer the influence that the third textile planar element has on the dampening properties of the other components of the floor covering is reduced. Therefore, a vertical dampening gradient with the associated comfortable sensation can still be established while a person is walking over the floor covering. By way of example, the third textile planar element may be connected to the second layer in a form-fitting connection or in a substance-to-substance connection. Additional advantages are cost savings due to the use of the cheaper flocculated foam.

In a further embodiment of the present invention the floor covering further comprises microencapsulated fragrances. Microencapsulated fragrances in the meaning of the present invention are substances in pure form, in solution or in mixtures which stimulate the sense of smell in a person and which are contained in capsules. The capsules have a maximum dimension of ≧1 μm to ≦1 mm, preferably of ≧10 μm to ≦100 μm. The microencapsulated fragrances may be incorporated into the first layer, into the first textile planar element and/or in optionally present fibers which protrude from the first textile planar element, for example as carpet tufting. In walking over floor covering according to the invention the capsules are destroyed and the fragrances are released. This creates a pleasant sensation in the respective persons and additionally contributes to the comfortable impression of the floor covering.

According to the invention it is encompassed that the described embodiments may not only exist in isolated form but may also be freely combined with each other.

A further aspect of the invention is a method for manufacturing a floor covering according to the invention, comprising the step of back-foaming the first textile planar element with a reaction mixture leading to the polymer foam of the first layer. By back-foaming a substance-to-substance connection between the first textile planar element and the first layer is easily achieved.

In an embodiment of the method according to the invention the reaction mixture comprises a polyol and an isocyanate. Therefore a viscoelastic polyurethane foam is formed during back-foaming. The monomers of the polyurethane foam may be selected from the group comprising polyether polyols and/or polyester polyols or their mixtures and at least difunctional isocyanates from the groups of aliphatic or aromatic isocyanates, furthermore conventional adjuvants, catalysts and stabilizers. Examples are given in the already cited patent documents or also in EP 0 331 941 A1.

In the method according to the invention it is also possible that the reaction mixture comprises a prepolymer and water. Suitable prepolymers are especially obtained on the basis of di- or polyisocyanates and polyols.

The present invention is further described with reference to the following drawings, wherein:

FIG. 1 shows a floor covering according to the invention. The first layer 1 comprises a viscoelastic polymer foam. With its lower side this layer 1 lies on the floor. On top of the layer 1 the first textile planar element 2 is located. A substance-to-substance connection joins the first layer 1 and the first textile planar element 2. On the upper side of the floor covering fibers 3 protrude outwards. The fibers 3 penetrate through the first textile planar element and extend into the first layer 1 with their lower end. Preferably the fibers are anchored to the first layer 1 by an elastomeric adhesive (not shown). By this the fibers cannot be torn out of the floor covering during use.

FIG. 2 shows another floor covering according to the invention. Besides the polymer foam, the first layer 1 located towards the floor now comprises a second textile planar element 2. Here, this is depicted as a woven fabric. The second textile planar element 4 is located in the lower end of the first layer 1. There is a substance-to-substance connection between the first textile planar element 2 and the first layer 1. Into the first layer 1 fibers 3 are incorporated which cover the surface of the floor covering. Due to its elasticity, the second textile planar element can absorb mechanical forces that arise from walking over the floor covering which are not absorbed or dampened by the first textile planar element 2 and the layer with viscoelastic polymer 1.

FIG. 3 shows another floor covering according to the invention. Beneath the first layer 1 a second layer 5 is located. This second layer comprises a polymer foam. The polymer foam has a higher compression load deflection and restoring forces than the viscoelastic polymer foam of the first layer 1. By this mechanical forces can be absorbed that arise from walking over the floor covering which are not absorbed or dampened by the first textile planar element 2 and the layer with viscoelastic polymer 1.

FIG. 4 shows another floor covering according to the invention. Beneath the first layer 1 a second layer 5 is located and beneath layer 5 a third textile planar element 6. This second layer 5 comprises a polymer foam. The polymer foam has a higher compression load deflection and restoring forces than the viscoelastic polymer foam of the first layer 1. The third textile planar element 6 comprises a woven fabric. The third textile planar element 6 and the second layer 5 allow for mechanical forces that arise from walking over the floor covering to be absorbed which are not absorbed or dampened by the first textile planar element 2 and the layer with viscoelastic polymer 1.

LIST OF REFERENCE NUMERALS

-   1 first layer, comprising viscoelastic polymer foam -   2 first textile planar element -   3 fibers -   4 second textile planar element -   5 second layer, comprising polymer foam -   6 third textile planar element

All the references described above are incorporated by reference in its entirety for all useful purposes.

While there is shown and described certain specific structures embodying the invention, it will be manifest to those skilled in the art that various modifications and rearrangements of the parts may be made without departing from the spirit and scope of the underlying inventive concept and that the same is not limited to the particular forms herein shown and described. 

1. A floor covering comprising a first textile planar element and a first layer which is at least partially connected to the first textile planar element over their surfaces, wherein the first layer comprises viscoelastic polymer foam, wherein the first textile planar element has a modulus of elasticity of ≧0.5 N/mm² to ≦2.5 N/mm², that in the first layer the viscoelastic polymer foam has a compression load deflection at 40% compression of ≧1 kPa to ≦10 kPa and that in the first layer the viscoelastic polymer foam has a hysteresis when determining the compression load deflection at 40% compression of ≧20% to ≦70%.
 2. The floor covering according to claim 1, wherein the viscoelastic polymer foam of the first layer is a polyurethane foam.
 3. The floor covering according to claim 1, wherein the viscoelastic polymer foam of the first layer is a cross-linked frothed foam from synthetic or natural latex.
 4. The floor covering according to claim 1, wherein the material of the first textile planar element comprises polyurethane and/or thermoplastic polyurethane.
 5. The floor covering according to claim 1, wherein the connection between the first textile planar element and the first layer is effected by an elastomeric adhesive.
 6. The floor covering according to claim 1, further comprising fibers which penetrate the first textile planar element and into the first layer and wherein the fibers are anchored in the first layer by an elastomeric adhesive.
 7. The floor covering according to claim 1, wherein the First layer additionally comprises an embedded second textile planar element which has a modulus of elasticity of ≧1000 N/mm² to ≦2000 N/mm².
 8. The floor covering according to claim 1, further comprising a second layer arranged on the side of the first layer which is opposite to the first textile planar element and which is at least partially connected to the first layer, wherein the second layer comprises polymer foam which has a compression load deflection at 40% compression of ≧15 kPa to ≦150 kPa.
 9. The floor covering according to claim 8, further comprising a third textile planar element which has a modulus of elasticity of ≧1000 N/mm² to ≦2000 N/mm², wherein the third textile planar element is arranged on the side of the second layer which is opposite to the first layer and wherein the third textile planar element is at least partially connected to the second layer.
 10. The floor covering according to claim 1, further comprising microencapsulated fragrances.
 11. A method for manufacturing a floor covering according to claim 1, comprising the step of back-foaming the first textile planar element with a reaction mixture leading to the polymer foam of the first layer.
 12. The method according to claim 11, wherein the reaction mixture comprises a polyol and an isocyanate.
 13. The method according to claim 11, wherein the reaction mixture comprises a prepolymer and water. 